My 87 535i has a leaking brake booster, right on the bottom where the two bolts are holding the master cylinder. I recently replaced the brake accumulator, and it was fine without any fluid leaking, but now it's quite bad. A new unit costs close to 300 dollars, so most likely I will have to pick-up a used unit.
Before I start working on it, is there anything other that i can check out? Also my power steering pump is whining, prior to the brake accumulator change all was good.